The present invention relates generally to nuclear medicine imaging, and more particularly to molecular breast imaging using nuclear medicine.
U.S. Pat. No. 8,115,171, assigned to General Electric Company and titled “Gamma Camera for Performing Nuclear Mammography Imaging” (herein incorporated by reference), describes a system for performing “molecular breast imaging”, or “MBI”. MBI typically involves the injection of a radiotracer into a patient wherein the radiotracer is carried by the bloodstream throughout the patient's body while emitting high-energy gamma photons which can be detected by a detection and imaging system, such as the system of CZT-based detectors described in the aforementioned patent. Nuclear imaging systems (also called molecular imaging systems) such as described in the aforementioned patent work by detecting the distribution of gamma ray emanations throughout the patient's body or from within a specific region of interest (ROI). Areas where the gamma ray emanations are remarkably higher than would be the case for normal tissue at that area indicate an increased amount of uptake of the radiotracer in that tissue, possibly indicating cancerous tissue, while areas where the gamma ray emanations are remarkably lower than would be the case for normal tissue at that area indicate a decreased amount of uptake of radiotracer in that tissue area, possibly indicating necrotic or dead tissue. Thus, MBI utilizes nuclear/molecular imaging focused on the breast and surrounding ROIs (e.g., the axillary lymph nodes), primarily to detect or screen for breast cancer.
FIG. 1 illustrates the typical workflow involved in conventional MBI, which is very similar to the workflow involved in X-ray based mammography. In FIG. 1A, a patient's breast (in this case, the patient's right breast 16) is positioned between an upper gamma detector 12 and a lower gamma detector 14 (or, the upper and lower detectors 12/14 are positioned so as to be adjacently above and below the breast, respectively) and the detectors 12/14 are moved toward each other so as to immobilize and/or lightly compress the selected breast. In FIG. 1A, the detectors are oriented essentially directly above and below the breast, in what is known in the art as the cranio-caudal (CC) orientation. Once the detectors are in place in this orientation for sufficient time to gather enough gamma photons for subsequent image reconstruction, the next step in the workflow is to move the detectors apart from each other and place them in the mediolateral-oblique (MLO) orientation, as shown in FIG. 1B. Here again, the detectors 12/14 may immobilize and/or lightly compress the breast and remain in position long enough to receive sufficient gamma photon counts. Then, detectors 12/14 are moved apart and the patient and/or detectors are positioned such that the other breast 18 can be imaged, such as in the CC orientation as illustrated in FIG. 1C. The final step is then to reorient the detectors to the MLO orientation, as shown in FIG. 1D. Those skilled in the art will recognize that other sequences or workflows other than that illustrated in FIGS. 1A-1D may also be performed. For example, both CC orientations may be done first, and then the two MLO orientations, or any combination of FIGS. 1A-1D.
In the conventional prior art MBI workflows exemplified by FIG. 1, and as described in the aforementioned patent, only one pair of detectors is used. This is similar to the systems utilized by conventional X-ray based mammography, wherein one pair of paddles/detectors is used to compress and image one breast at a time. However, one drawback for MBI workflows in particular is that it can take quite a long time at each of the four positions shown in FIGS. 1A-1D to gather sufficient gamma photon counts to produce a suitable image. (Typically it takes much longer for a pair of gamma detectors to produce a suitable image than it takes for a pair of X-ray paddles/detectors to do so.) In addition to just the amount of time it takes, there is also the amount of discomfort that the patient must endure while the full workflow is completed. It would be desirable, therefore, to provide an improved MBI system and workflow which is quicker so as to reduce the amount of time spent and discomfort experienced by patients undergoing an MBI imaging procedure.